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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1r00TI-006OrJ-2n; Mon, 06 Nov 2023 14:20:56 +0000 Date: Mon, 6 Nov 2023 14:20:56 +0000 From: Matthew Wilcox To: Kefeng Wang Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, David Hildenbrand , linux-s390@vger.kernel.org Subject: Re: [PATCH v2 06/10] mm: memory: use a folio in zap_pte_range() Message-ID: References: <20231104035522.2418660-1-wangkefeng.wang@huawei.com> <20231104035522.2418660-7-wangkefeng.wang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B1B60180011 X-Stat-Signature: zc1h8apdonfjwou3zjbiu451a8xawqxg X-Rspam-User: X-HE-Tag: 1699280470-853400 X-HE-Meta: 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 Kohdh2mg we/2q1TVcCo2ORELfyM0t3kpbcDbOj5XVfpqmZMe5Y5jO8nCNmxpwTJushiXMh4mcqzRI80ecHnE1WdZDYf8L680L/QfHmquZSmuFO9vijQ95A7D+TKnYhC8HpsUQvKUYvYaIqI9KGZHHy9PFgksloj39xqcZY4SthJDnNoh4MvhKuuG5Zfymg/gpuw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Nov 06, 2023 at 10:30:59AM +0800, Kefeng Wang wrote: > On 2023/11/5 1:20, Matthew Wilcox wrote: > > > - page_remove_rmap(page, vma, false); > > > - put_page(page); > > > + page_remove_rmap(&folio->page, vma, false); > > > + folio_put(folio); > > > > This is wrong. If we have a PTE-mapped THP, you'll remove the head page > > N times instead of removing each of N pages. > > This is device private entry, I suppose that it won't be a THP and large > folio when check migrate_vma_check_page() and migrate_vma_insert_page(), > right? I don't want to leave that kind of booby-trap in the code. Both places which currently call page_remove_rmap() should be left as referring to the page, not the folio.